Blender keeps flashing not responding
There are a number of things that could cause this problem. It could be an old video driver. It could be a corrupt download.

The first thing I'd try is browse to C:\Users[user]\AppData\Roaming and delete the folder called "Blender Foundation." This is where Blender keeps all kinds of caches, settings, configurations, etc. Deleting this folder is like resetting Blender to the factory default configuration.

If that doesn't help, post your problem on BlenderArtists.org with a bit more detail about what "flashing" means, what GPU you have, when you last updated your drivers, and whether you're on a laptop or desktop.

Hope that helps!